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Geology Department Colloquium, Mar 25

Speaker: Heather Wright, Cascade Volcano Observatory

Title: “Holocene rhyolite eruptions Salton Buttes, CA”

Please join us: Tuesday, March 25th @ 11AM in Edmunds 130

Abstract: Five Holocene rhyolite domes lie along the southern margin of the Salton Sea, California. The domes are aligned parallel to the axis of spreading along the boundary between the Pacific and North American plates in the Salton Trough pull apart basin. These volcanic domes are spatially associated with a broad area of high heat flow (tens of kilometers wide) and active geothermal energy production in the Salton Sea Geothermal Field.

In 2012, after the USGS established the California Volcano Observatory, we began to revisit fundamental questions regarding the hazard potential for volcanic activity at the Salton Buttes. What is the frequency and style of eruptions at the Salton Buttes? What type of magma was erupted?  Where and for how long was this magma stored prior to eruption?  Here, I discuss some of the answers to these questions: only rhyolite makes it to the surface, but basalt is found at depth; all domes erupted in the Holocene, but preceding eruptions occurred >400k years ago; shallow magma storage regions appear to be small, transitory systems, thermally waxing and waning many times over tens of thousands of years.